Ignition device



United States Patent C) 3,025,363 IGNITION DEVICE Laurence D. Bakke, Plymouth, Mich., assignor to Continental Motors Corporation, Muskegon, Mich., a corporation of Virginia Filed Dec. 28, 1959, Ser. No. 862,219 3 Claims. (Cl. 200-30) My invention relates to ignition timing devices and more particularly to an assembly of a breaker point actuating cam and its operating shaft arranged to permit angular adjustment of said cam on the shaft.

An object of the present invention is to facilitate ignition timing by providing a readily adjustable breaker actuating cam.

Another object of the invention is to simplify breaker actuating cam and shaft assemblies by providing an improved construction in which angular adjustment is available for timing purposes but in which the cam can be readily securely locked to its shaft.

A further object of the invention is to provide inexpensive ignition timing devices for small engines by constructing a breaker actuating cam of sintered material or the like and means for readily securing such a cam on its operating shaft in such fashion that stresses tending to fracture the sintered or other fragile material are materially reduced.

For a more complete understanding of the invention, reference may be had to the accompanying drawing illustrating a preferred embodiment of the invention in which like reference characters refer to like parts throughout the several views and in which FIG. 1 is a fragmentary perspective view of a small internal combustion engine showing the ignition timing device embodying the present invention.

FIG. 2 is an exploded elevational view of the preferred cam and shaft incorporated in the device of FIG. 1.

FIG. 3 is a longitudinal cross-section of the cam and shaft as assembled, taken on the line 3-3 of FIG. 2.

FIG. 4 is a cross sectional view of the cam taken substantially on the line 4-4 of FIG. 2.

As illustrated in FIG. 1, a small internal combustion engine is provided with a preferred ignition timing device 11, shown here with the cover removed for clarity, comprising a breaker point assembly 12 and a cam 13 which rotates to actuate or make and break the breaker points. The cam 13 is rotatably operated by a drive shaft 14, shown in FIGS. 2 and 3, driven by and in timed relation to the engine 10 in any conventional fashion. The cam 13 is adapted to be angularly adjusted with respect to the shaft 14 for timing the operation of the breaker point assembly 12.

The cam 13 is preferably made of inexpensive sintered metal or the like, which material is easily fractured if undue stresses are imposed and thus poses problems in securing same to the shaft 14, since it must be locked against slippage and yet should be readily adjustable when desired without being disassembled.

To solve these problems, I have provided the cam 13 with a cylindrical recess 20 into which tits the end of the shaft 14. The inner end of the recess 20 has an annular rounded groove 21. The end of the shaft 14 has an annular tapered axially extending flange 22 which is constructed to make a wedge tit in the groove 21. The end of the shaft 14 has a tapped hole 23 for receiving a screw 24 which extends through a hole 25 extending axially from the inner end of the cam recess 20 and disposed concentrically with respect to the recess 20 and the groove 21.

When the screw 24 is tightened, it acts to wedge the flange 22 into the groove 21, preventing angular displacement of the cam 13 with respect to the shaft 14. The wedging pressure, however, is directed radially inwardly against the portion of the recess inner end between the groove 21 and the hole 25 and being resisted by the presence of the screw 24 will not ordinarily crack or otherwise damage the cam 13 even if the screw 24 is tightened excessively. Yet, when the screw 24 is loosened slightly, the wedge lock is readily released by hand to permit angular adjustment of the cam 13 on the shaft 14.

Although I have described only one embodiment of my invention, it will be apparent to one skilled in the art to which the invention pertains that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In an internal combustion engine, ignition timing means comprising breaker points, a cam for operating said breaker points and having a cylindrical mounting recess, a drive shaft having a cylindrical end insertable in said mounting recess to carry said cam and permitting angular adjustment of said cam on said shaft end, said cam recess having an inner end provided with an annular axially extending groove, said shaft end having a tapered annular axially extending flange adapted to make a substantially thin line contact wedge t with the inner annular edge of said groove and to lock said cam against angular displacement with respect to said shaft when the shaft end is forced axially into said recess, and means axially forcing said shaft end into said recess.

2. In an internal combustion engine, ignition timing means comprising breaker points, a cam for operating said breaker points and having a cylindrical mounting recess, a drive shaft having a cylindrical end insertable in said mounting recess to carry said cam and permitting angular adjustment of said cam on said shaft end, said cam recess having an inner end provided with an annular axially extending groove, said shaft end having a tapered annular axially extending ange adapted to make a substantially thin line contact wedge fit with the inner annular edge of said groove and to lock said cam against annular displacement with respect to said shaft when the shaft end is forced axially into said recess, said cam having a hole bored axially outwardly from the inner end of said recess and of a diameter smaller than said groove, said shaft end having an axially extending tapped hole, and a screw extending through said cam hole and engaging in said tapped hole whereby tightening of said screw axially forces said shaft end flange into said recess.

3. The ignition timing means as defined in claim 1 and in which said groove is arranged to provide clearance between same and the inner surface of the shaft end flange which extends into said groove.

References Cited in the tile of this patent UNITED STATES PATENTS 1,415,369 Lehman May 9, 1922 1,854,150 Lowser Apr. 12, 1932 2,190,603 Miller Feb. 13, 1940 2,209,036 Reis July 23, 1940 2,795,443 Gratzmuller June 11, 1957 2,879,346 Mason Mar. 24, 1959 

